a. Field of the Invention
The present invention relates to household and commercial vacuum cleaners for removing dirt from flooring and other surfaces, and, more particularly, to a canister-type vacuum cleaner in which the body of the vacuum cleaner is supported above the floor's surface on a cushion of air exhausted from a vacuum motor that also provides vacuum airflow for the assembly.
b. Related Art
Canister-type vacuum cleaners in which the main body of the vacuum cleaner is supported on a cushion of exhaust air have existed within the art, but with varying degrees of success. Perhaps the most famous is the Hoover™ Constellation™ which in its original form was introduced in the mid-1950s and produced into the 1970s, and which was re-released more recently in modified form. Another example is the more recent Airider™ floating vacuum. These and other examples of “floating” air cushion vacuum cleaners that have been proposed or manufactured are shown in the following U.S. and foreign patents:
U.S. Pat. No. 6,209,167 (Rooney et al.)
U.S. Pat. No. 8,015,658 (Tan)
U.S. Pat. No. D665,546 (Van Den Heuvel)
US 2013/0014342 (Greer)
WO2011072388A (Greer)
CA2665962A1 (Greer)
Air cushion vacuum cleaners, also referred to from time-to-time herein as floating vacuum cleaners or hovering vacuum cleaners, offer many potential advantages over their conventional counterparts in which the canister is supported on wheels or casters. For example, a canister floating on a cushion of air is free to move in any direction without the resistance caused by wheels or casters having to pivot or being constrained to turning through an arc; in effect, the air cushion enables the canister to pivot and turn freely in either direction with essentially no resistance from the standpoint of the operator. The air cushion also enables the canister to glide over the floor surface with no rolling resistance or friction as compared with wheels or casters, and without being impeded by or becoming “bogged down” in the pile of carpeted floors. The absence of wheels supporting the weight of the canister also reduces the potential for marring or otherwise marking hardwood flooring or similar surfaces.
In practice, however, the advantages described above have only been partially achieved owing to limitations and drawbacks of prior air cushion vacuum cleaners. A common drawback has been the lack of stability and inability to maintain a level orientation during use, due in significant part to the lack of compensation for variances in the canister's center of gravity caused by both external loads as well as by shifting internal loads as dirt/dust accumulates inside the canister.
For example, only the canister assembly of the vacuum cleaner, which serves to house the motor and the bag or other dust/dirt collector, is ordinarily supported on the cushion of air, with suction being supplied from the canister through a hose to a nozzle that the user moves over the floor surface, furniture, drapes, and so on in order to remove dirt and dust. In newer and more effective machines, such nozzles frequently include motors and brushes of their own, commonly referred to as “power nozzles.” Power nozzles require a relatively heavy, electrified “power hose” which adds significant weight to the front of floating canisters, more so than the lighter, non-electric hoses commonly used with non-powered nozzles and attachments. The weight of the hose combined with the pulling action in various directions as the operator moves the nozzle assembly about the floor and other surfaces tends to upset the orientation of the canister and cause the air to escape more on one side or the other, or more at the front or rear or vice versa, with the result that the canister may tilt to the point of contacting or “digging into” the carpet or other surface, and thereby compromise its ability to turn and move without resistance. Additionally, the heavy power hose may be exchanged from time-to-time for a lighter non-electric hose for use with non-powered accessories, for example, thus changing the load on the front of the canister and impacting its ability to maintain a horizontal orientation. Furthermore, while prior floating canisters may be able to glide more-or-less freely over uniform surfaces, they frequently encounter difficulties at transitions, such as between hard and carpeted floor surfaces or over thresholds, where the flow of air creating the cushion under the canister may be disrupted or otherwise compromised in one area or another and the resulting uneven lift tends to cause the canister to dive or tilt in an undesirable manner.
Other difficulties in prior designs have included inefficient creation of the air cushion and related problems, along with power requirements and added weight. While sophisticated by standards of the day, the inherent weightiness and limited shapes available in the stamped metal construction used in the classic Hoover™ Constellation™ vacuum combined to require a powerful motor in order to generate the necessary lift (the size of the motor in itself adding to the weight), resulting in a noisy and heavy machine that is difficult to lift and carry up stairs or otherwise move about manually. Modern plastic construction has allowed more recent designs to enjoy somewhat reduced weights, as well as more sophisticated airflow contours and paths. Yet problems such as “fluttering” (where an excessive weight-load at the canister's rear causes an escape of the air cushion frontward in rapid bursts) or “nose diving” (where an excessive weight-load at the canister's front causes an escape of the air cushion rearward) remain, due in large part to a failure to compensate for the shifting center of gravity caused by weight-load variations, as well as inefficient development and distribution of the air cushion on the canister's underside.
Accordingly, there exists a need for an air cushion-supported canister for vacuum cleaners that creates, distributes and maintains the air cushion in an efficient manner, so as to both improve performance and reduce the amount of power that is required to support the canister. Furthermore, there exists a need for such an air cushion-supported canister assembly having a reduced weight so that the canister is both more easily supported by the air cushion, and is light enough to be carried by the user upstairs and to various locations around the home or office. Still further, there exists a need for such an air cushion-supported canister assembly having improved stability and floating performance when maneuvering in conjunction with a vacuum hose cleaning nozzle. Still further, there exists a need for such an air cushion-supported canister assembly having improved stability and floating performance while experiencing variances in the canister's weight load, such as when a bag or dirt compartment fills during use, or when the front of the canister is lightly weighted with a non-electrified hose compared to being more heavily weighted with an electrified power hose. Still further, there exists a need for such a canister assembly that is able to move smoothly over transitions and changes in height of floor surfaces, such as between carpeted and hard floor surfaces and over irregular thresholds, for example.